WO2024052137A1 - Dispositif et procédé de traitement d'un matériau au moyen d'impulsions laser qui sont introduites statistiquement et spatialement autour d'une valeur cible spatiale - Google Patents

Dispositif et procédé de traitement d'un matériau au moyen d'impulsions laser qui sont introduites statistiquement et spatialement autour d'une valeur cible spatiale Download PDF

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Publication number
WO2024052137A1
WO2024052137A1 PCT/EP2023/073377 EP2023073377W WO2024052137A1 WO 2024052137 A1 WO2024052137 A1 WO 2024052137A1 EP 2023073377 W EP2023073377 W EP 2023073377W WO 2024052137 A1 WO2024052137 A1 WO 2024052137A1
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WIPO (PCT)
Prior art keywords
laser
laser pulses
pulses
distribution
clock signal
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PCT/EP2023/073377
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German (de)
English (en)
Inventor
Daniel Grossmann
Jonas Kleiner
Marc Sailer
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Trumpf Laser Gmbh
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Publication of WO2024052137A1 publication Critical patent/WO2024052137A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
    • B23K26/062—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam
    • B23K26/0622—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam by shaping pulses
    • B23K26/0624—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam by shaping pulses using ultrashort pulses, i.e. pulses of 1ns or less
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
    • B23K26/062—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam
    • B23K26/0626—Energy control of the laser beam
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/08—Devices involving relative movement between laser beam and workpiece
    • B23K26/082—Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/20—Bonding
    • B23K26/21—Bonding by welding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/36—Removing material
    • B23K26/362—Laser etching
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/36—Removing material
    • B23K26/38—Removing material by boring or cutting

Definitions

  • the present invention relates to a device and a method for processing a material using laser pulses from a pulsed laser.
  • regular structures When processing a material with a pulsed laser, regular structures often arise, for example due to a beat between the repetition rate and other process parameters such as the feed rate and the number of repetitions of material passes. Such regular structures can, for example, lead to interference effects that disrupt the visual impression of the processed material.
  • a method for processing a material with the features of claim 1.
  • Advantageous further developments result from the subclaims, the description and the figures. Accordingly, a method for processing a material using laser pulses from a pulsed laser is proposed, wherein the laser pulses are introduced into the material to process the material. According to the invention, the laser pulses are introduced into the material in a spatially statistically distributed manner around a spatial target value.
  • the material to be processed can be a material such as a metal foil, a polymer or a plastic.
  • the material to be processed can also be a semiconductor, for example an elementary semiconductor such as silicon or germanium, or a III-V semiconductor such as gallium arsenide, or an organic semiconductor or any other type of semiconductor.
  • the material can be a silicon wafer.
  • the material can be a layer system, whereby each layer can be selected from the group of metals, polymers, plastics or semiconductors.
  • the material can also be a glass, for example sapphire.
  • the laser provides the laser pulses of the laser beam, with the individual laser pulses forming the laser beam in the beam propagation direction.
  • the laser can be an ultra-short pulse laser, the pulse length of the individual laser pulses being preferably shorter than 10ns, preferably shorter than 500ps.
  • the laser can also provide laser bursts, with each burst comprising the emission of several laser pulses. For a certain time interval, the laser pulses can be emitted very closely, at intervals of a few picoseconds to nanoseconds.
  • the laser bursts can in particular be GHz bursts, in which the sequence of successive laser pulses of the respective burst takes place in the GHz range.
  • the laser pulses are introduced into the material, allowing the material to be processed. Introducing can mean that the energy of the laser beam is at least partially absorbed in the material.
  • the focus of the laser beam can lie above the surface of the material to be processed in the beam propagation direction or lie below the surface in the volume of the material to be processed. The focus position can also be exactly on the surface of the material to be processed.
  • the term “focus” can generally be understood as a targeted increase in intensity, whereby the laser energy converges into a “focus area”.
  • the term “focus” will be used below regardless of the beam shape actually used and the methods used to bring about an increase in intensity.
  • the location of the intensity increase along the beam propagation direction can also be influenced by “focusing”.
  • the increase in intensity can be virtually point-shaped and the Focus area has a Gaussian-shaped intensity cross section, as provided by a Gaussian laser beam.
  • the intensity increase can also be designed in a line shape, resulting in a Bessel-shaped focus area around the focus position, as can be provided by a non-diffracting beam.
  • other more complex beam shapes are also possible whose focus position extends in three dimensions, such as a multi-spot profile of Gaussian laser beams and/or non-Gaussian intensity distributions.
  • the material heats up in accordance with the intensity distribution of the laser and/or changes into a temporary plasma state due to the electromagnetic interaction of the laser with the material.
  • non-linear absorption processes can also be used, which become accessible through the use of high laser energies or laser intensities.
  • the material is modified accordingly, particularly in the focus of the laser, as that is where the intensity of the laser beam is greatest.
  • part of the material can be separated from the composite of the material, for example melting or being evaporated.
  • known processing processes are possible, which are known, for example, as laser drilling, percussion drilling or laser ablation.
  • material modifications can also be introduced or applied to the material.
  • a material modification can, for example, be a permanent modification of the network structure of the material or the (local) density of the material, which originates from the local heating generated by the direct laser irradiation and the subsequent cooling and/or electronic relaxation processes.
  • the material modification in or on the material can be, for example, a modification of the structure, in particular the crystalline structure and/or the amorphous structure and/or the chemical structure and/or the mechanical structure, of the material.
  • the material modification is in the material when it is introduced substantially into the volume of the material.
  • the material modification is on the material if the material modification essentially modifies the surface of the material.
  • a material modification can be introduced or applied both in and on the material, depending on the focus position and the beam profile of the laser beam.
  • a material modification can also be the direct change of a physical property, for example the strength and/or the bending strength and/or the tolerance of the material to bending forces and shear forces as well as shear and tensile stresses.
  • a material modification can in particular also be a local change in density, which can depend on the material selected. For example, density variations in the material can create tension and compression zones that have a higher material hardness than the untreated material. It is also possible for a material modification to determine the optical properties of the material, for example by scattering light passed through a transparent material and making the material appear diffuse.
  • the laser pulses are introduced into the material in a spatially statistically distributed manner around a spatial target value.
  • the spatial target value can be given, for example, by a point or a coordinate on the material.
  • the spatial target value can also be given by a trajectory or a group of points on the material.
  • the spatial target value can correspond to the actually intended processing trajectory, for example a weld seam to be laid, a separating contour to be introduced and/or a surface treatment to be introduced.
  • the spatial target value is the spatial position at which the material processing has conventionally taken place and the laser pulses for processing have been entered accordingly.
  • Laser pulses that are spatially statistically distributed around a spatial target value therefore have a statistical distribution of spatial distances from the spatial target value, so that the spatial distribution means that the laser pulses are introduced into the material at irregular intervals from the spatial target value.
  • the laser pulses are also at different distances from one another.
  • the spatial distribution of the distances results in a spatial frequency distribution of the introduced laser pulses in the spatial frequency space, for example via a Fourier transformation.
  • both the distances to the spatial target value and the spatial frequency distribution can correspond to a statistical distribution. This has the advantage that the laser pulses are introduced into the material at an irregular distance from one another, so that disruptive optical effects, such as interference, are reduced or avoided.
  • the laser pulses can also be introduced into the material in an energetically statistically distributed manner around an energetic target value.
  • the energetic setpoint can, for example, be a correspondingly selected energy. Due to the different energies introduced, the material modifications can, for example, have different sizes. This means that regularly occurring patterns on the processed material surface or in the processed material can be further interrupted.
  • the laser pulses can be statistically distributed in at least one spatial dimension.
  • the laser pulses can have a statistical distribution, for example, along an x-axis or a y-axis or a z-axis.
  • the laser pulses can have such a statistical distribution in two or three dimensions.
  • the laser pulses can have a Gaussian distribution along an x-axis.
  • the distance between the laser pulses along the x-axis is then also Gaussian distributed, for example. This is because the Fourier transform of a Gaussian function is also a Gaussian function.
  • the laser pulses can also have a Gaussian distribution along an x and a z axis. Then the laser pulses are randomly distributed along the material surface and the material depth.
  • the laser beam and the material can be moved relative to each other with a feed.
  • Relatively displaceable means that both the laser beam can be translated translationally relative to a stationary material and the material can be displaced relative to the laser beam, or there is a movement of both the material and the laser beam.
  • the focus of the laser beam to be placed at different locations on the material in order to introduce laser pulses.
  • the laser pulses are particularly on the so-called feed trajectory.
  • the feed trajectory can be straight or curved.
  • the local feed direction is always the y-direction, while the z-axis is parallel to the surface normal and the x-axis is aligned perpendicular to the y-axis parallel to the material surface.
  • the laser beam can be moved along with a feed while the laser pulses are emitted into or onto the material.
  • the laser pulses can be emitted with a temporal statistical distribution around a temporal setpoint during the feed.
  • a temporal statistical delivery of the laser pulses can lead to a spatially statistical distribution of the laser pulses in the material, with the feed then preferably taking place uniformly.
  • the pulses are spaced apart in time.
  • a frequency of the laser pulse output in the frequency space results from the time course via a Fourier transformation. If the time intervals between the laser pulses are also different, the laser pulses are distributed around the frequency of the laser pulse emission in the frequency space.
  • Laser pulses that are statistically temporally distributed around a target value therefore have a distribution of time intervals from one another, so that the temporal distribution results in an irregular introduction of the laser pulses into the material.
  • the setpoint determines the time scale within which the laser pulse emission takes place, while the statistical distribution, so to speak, determines the fine structure of the laser pulse emission. If the laser beam and the material are moved with a feed during the application of the laser pulses, the temporal statistical distribution around the target value results in a spatial statistical distribution around a target value.
  • the temporal setpoint can be, for example, a basic frequency of the laser or a system clock.
  • the setpoint can also be any trigger signal.
  • the statistical distribution of the laser pulses can correspond to a Gaussian distribution or a uniform distribution or a triangular distribution or a sawtooth distribution.
  • the spatial target value can correspond to the expected value of the Gaussian distribution and the statistical distribution can be characterized by a half-width.
  • the expected value can be a straight trajectory on the material and the Standard deviation can be 10pm, then more than 68% of the laser pulses are emitted around the trajectory within ⁇ 10pm.
  • the spatial statistical distribution may be a uniform distribution, with each distance occurring in an interval around a target value with the same probability.
  • the target value can be given by the center of the material.
  • the interval can be ⁇ 100pm around the center of the material surface. Then it is equally likely that the laser pulses have a distance of 7pm, -8.5pm, 9pm, 9.3pm, -12pm, 56.2pm, -99pm and 100pm to the center.
  • the spatial statistical distribution can be a triangular distribution.
  • the spatial target value can be the most probable value and the range of fluctuation is determined by the length of the legs of the probability distribution.
  • the fluctuation range can be -5pm to +10pm, while the setpoint can be 20pm relative to a point on the feed trajectory that is currently being approached.
  • the triangular distribution may exhibit intrinsic asymmetry.
  • the spatial statistical distribution can be a sawtooth distribution.
  • the most likely value can then be the spatial target value and the range of fluctuation is determined by the length of the falling edges of the probability distribution.
  • the setpoint can be 30pm while the fluctuation range is +11pm.
  • the laser pulses then have a spatial distance of 30 pm to 41 pm.
  • the temporal target value can correspond to the expected value of the Gaussian distribution.
  • the expected value can be given by a specific point in time and the standard deviation can be 20ps, then more than 68% of the laser pulses around the trajectory are emitted within ⁇ 20ps.
  • the setpoint can be given by a frequency, for example the fundamental frequency of the laser or a regular system clock. The laser pulses can then be distributed in the time-frequency space around the fundamental frequency according to an expected value.
  • the energetic statistical distribution can be a sawtooth distribution.
  • the setpoint can be 0.1 mJ while the fluctuation range is +0.4 mJ.
  • the laser pulses then have energy in the range from 0.1 mJ to 5 mJ.
  • the laser pulses can have a spatial statistical distribution and an energetic statistical distribution and/or a temporal statistical distribution.
  • the statistical distribution can also be composed of different statistical distributions. For example, it is possible to overlay a normal distribution and a uniform distribution. However, it may also be the case that the statistical distribution is distorted.
  • the Gaussian distribution can also have a skew.
  • the statistical distribution of the laser pulses makes it particularly easy to interrupt and randomize a regular structure.
  • the statistical distribution can be adjustable.
  • the half-width of a Gaussian distribution can be adjustable or the expected value of the distribution can be adjustable.
  • the time distribution can be set more precisely than 1 ps. This can mean that the temporal delivery of the laser pulse is set to an accuracy of 1 ps, so that the temporal laser pulse delivery follows the desired temporal distribution.
  • the feed speed can be selected so that laser pulses emitted immediately one after the other do not overlap.
  • the diameter of the laser focus is 5pm and the repetition rate of the laser pulses is 10kHz. This results in a minimum feed speed of 0.5 m/s.
  • variation of the spatial and/or temporal distribution can be adapted, for example, in curves that are typically traveled at a lower speed. This can prevent laser pulses introduced one after the other from overlapping in the workpiece.
  • the time intervals remained the same, successive laser pulses would overlap in the material at a low speed.
  • the temporal statistical distribution is broadened, for example by increasing the standard deviation and/or the expected value, such an overlap can be avoided.
  • the statistical distribution of the laser pulses can be adjusted depending on the current feed speed.
  • a uniform distribution of the laser pulses can be used, since the spatial distance between the laser pulses must be kept as large as possible in order to avoid a pulse overlap.
  • it can make sense to have a Gaussian distribution of the laser pulses so that the laser pulses are more concentrated on the feed trajectory.
  • the fluctuation range for example the expected value
  • the fluctuation range to be set smaller at higher feed speeds, i.e. at higher feed speeds, so that the actual spatial fluctuation range of the laser pulses on the material is always similar or the same.
  • the temporal statistical distribution can be adapted to the feed rate, so that, for example, the spatial statistical distribution generated by the laser pulses on the material remains the same or changes while the feed rate is varied.
  • the statistical distribution can be adjusted depending on the process phase.
  • a first statistical distribution can make sense for a first machining process and a second statistical distribution can make sense for a second statistical process.
  • machining a surface when machining a surface, it may make sense to use a meandering feed trajectory, with the laser pulses spatially distributed in a Gaussian shape around the meander. By moving adjacent lines of the meander anti-parallel to each other and overlapping the Gaussian distribution on the flanks, a homogeneous processing of the material can be achieved on the surface.
  • the material is processed in advance in the direction of the feed trajectory, i.e. laser pulses are partially placed in front of the target position of the laser beam.
  • a spatial sawtooth distribution can be used in order to achieve a particularly clean separation of the material.
  • laser pulses would be individually directed in front of the current position of the laser beam in the direction of the feed direction, so that the material is already specifically weakened there. Accordingly, targeted crack propagation could take place from the current location of the laser beam, which, for example, corresponds to the target value, to the isolated position of the laser pulse.
  • the present method according to the invention can be used advantageously in numerous machining processes.
  • the processing process of the material can be a separation process or a deep engraving process in which material is removed in multiple passes with a small spatial overlap of successive laser pulses.
  • the laser pulse emission in the feed direction By randomizing the laser pulse emission in the feed direction, an even distribution of the laser pulses can be achieved, resulting in a high-quality cutting edge or engraving.
  • the engraving is then free of periodic structures, so that there are no disturbing diffraction phenomena that could disturb the optical impression.
  • the machining process can also be used for metal structuring or surface removal.
  • the visual impression depends heavily on the surface quality.
  • the randomization of the laser pulses ensures that no undesirable patterns are impressed on the surface of the material.
  • dimple structuring of a surface for anti-glare functionalization Another important processing process is the so-called dimple structuring of a surface for anti-glare functionalization.
  • dimples or craters can be impressed on the surface of the material by the laser pulses, where incident light is scattered. This allows the material to have a matt surface finish.
  • the method according to the invention can be used to achieve particularly advantageous optical and haptic target properties of a material after dimple structuring.
  • a dimple structure can be used when processing a display glass, in particular a cover glass.
  • the sparkle a measure of irregular intensity and color fluctuations, can be adjusted.
  • the sparkle depends on the size of the dimples.
  • the sparkle can be set to less than 4%. If the glass is placed over a display with a particularly high resolution, it is advantageous to reduce the size of the dimples to ensure a low sparkle value.
  • Another important parameter is the “Distinctness of Image”. This parameter is a measure of the clarity of the user information to be read.
  • the “Distinctness of Image” scales inversely with the scattering or diffusion of the light through the display cover glass.
  • the “Distinctness of Image” can be set to more than 70% using the method according to the invention.
  • the “Distinctness of Image” can be adjusted via the area filling of the display glass with the dimples, with the area filling preferably being between 40% and 95% of the display area.
  • diffusion is a measure of the scattering strength of the display glass.
  • the diffusion also depends on the shape and nature of the individual dimples.
  • the diffusion of the display glass can be set to more than 22%, for example.
  • the method according to the invention can be used to avoid a moiré effect, which typically occurs when the pixel period of the display panel is of the same order of magnitude as the period of the dimple arrangement.
  • a moiré effect typically occurs when the pixel period of the display panel is of the same order of magnitude as the period of the dimple arrangement.
  • the material modification can also be designed as bumps, i.e. increases in the material, which arise from the short-term melting and thermal expansion of the material.
  • the material modifications in particular the elevations and depressions, also achieve a haptic change in the material surface.
  • roughness can serve as a haptic target value.
  • the haptic impression can be adjusted by the density of the modifications. A higher density typically creates a stronger or rougher haptic impression.
  • So-called laser-induced periodic surface structures (hereinafter referred to as “LIPSS”) can also be generated by successive interaction of the same material area with at least two laser pulses.
  • Dimples and LIPSS are suitable for functionalizing the surfaces of components, in particular optical properties, wetting properties and tribological properties can be influenced.
  • the method produces dimples with a diameter between 13pm and 20pm, with the laser-induced periodic surface structures having a periodicity between 650nm and 1000nm.
  • a device for processing a material comprising a system clock generator, which is set up to provide a system clock signal, a statistics generator, which is set up to receive the system clock signal, to impose a temporal statistical distribution on the system clock signal and to provide a statistics clock signal, a laser , which is set up to receive the statistics clock signal or the system clock signal and to emit a laser pulse when the clock signal is received, a feed device that is set up to move the laser beam and the material relative to one another and processing optics that are set up to move the laser beam to transfer it into a focus zone and introduce it into the material, whereby the material is processed.
  • the system clock generator can provide the clock in the entire device so that all devices used can synchronize to a common clock.
  • the system clock generator for example, outputs a pulsed basic signal with a basic frequency.
  • the basic signal of the system clock generator may correspond directly, for example, to the temporal setpoint of the statistical distribution of the temporal pulse output.
  • the basic signal must be passed through a suitable multiplier in order to provide the setpoint of the temporal pulse output.
  • the former is always assumed.
  • the system clock generator it is also possible for the system clock generator to only output isolated signal pulses as a system clock signal, i.e. the system clock signal does not have a fixed basic frequency.
  • the system clock generator can, for example, be installed in the pulsed laser itself and correspond, for example, to the repetition rate, or be an external pulse generator. However, it is also possible that the system clock appears irregular and merely represents a general trigger signal and is emitted by a feed device or a position offset device.
  • the statistics generator receives the system clock signal and can impose a statistical distribution on the signal pulses of the system clock signal. For example, the signal pulses can have a Gaussian distribution around the original signal pulses.
  • the statistics generator can be, for example, an FPGA or a computer or a microchip or an ASIC (application-specific integrated circuit) or a microcontroller. This makes it particularly easy to set different statistical distributions, for example.
  • the statistics clock signal can be received by the laser, which preferably has pulse-on-demand functionality. Accordingly, the laser emits a laser pulse every time it receives a pulse of the system clock signal. The emitted laser pulses therefore have the same time course as the pulses of the statistics clock signal. In other words, the pulse-on-demand signal from the system clock generator for the pulsed laser is manipulated with the statistics generator.
  • the statistical variation of the received pulses of the basic signal can be carried out by the statistics generator with a clock speed of over 1 MHz. This has the advantage that even with a very high clock rate, the statistics generator can still reliably impose the same statistical distribution on the pulses of the basic signal.
  • the device also has processing optics that can focus the laser beam into the material.
  • the processing optics can convert an angular offset into a spatial offset, so that a statistical spatial deflection is generated particularly easily in the case of a statistical angular deflection described further below.
  • the laser beam can be focused into/or onto the workpiece by means of the processing optics or a scanner unit, the processing optics having a numerical aperture of NA>0.01 and the scanner unit having a numerical aperture of NA ⁇ 0.1.
  • the processing optics has a numerical aperture between 0.01 and 0.2, in particular 0.04.
  • the numerical aperture NA essentially indicates the opening angle of the laser beam in focus, with a large numerical aperture meaning a large opening angle. This allows the extent of the focus zone in the beam propagation direction to be adjusted and thus also the size of the material modification in the beam propagation direction.
  • the device can also include a feed device which moves the laser beam and the material relative to one another.
  • the feed device can preferably comprise an axis device and/or a scanner device.
  • the material can be moved mechanically with the axis device, while the laser beam is moved over the material with a scanner device.
  • the axis device can be an XYZ table with stepper motor control.
  • the axle device is designed with piezo adjustments in order to achieve the fastest possible adjustment.
  • the scanner device can in particular be a galvano scanner.
  • the feed device is a roll-to-roll device.
  • the feed device can receive the system clock.
  • the system clock can be used to clock a stepper motor so that a certain number of steps are carried out per second. By setting a multiplier on the motor, the feed speed can be set particularly easily.
  • the system clock can be a regular clock with which the scanner periodically deflects the laser beam over the material.
  • the feed device can receive the statistics clock signal.
  • the feed device can then form an uneven feed trajectory. This also creates a statistical distribution around the feed trajectory, especially in the direction of the feed trajectory.
  • the feed device to provide the system clock.
  • the feed device thus itself outputs the system clock, which is sent to the statistics generator.
  • the feed device can output a system clock signal every time it has been moved a certain length.
  • the laser pulses can then be emitted automatically depending on the distance traveled and independently of the feed speed.
  • the current speed can be estimated from the position-synchronous signal in order to make an adjustment to the statistical distribution if necessary
  • the device can have a position offset device which is set up to receive the statistical clock signal and to impose a spatial statistical distribution around a spatial target value on the laser pulses.
  • the position offset device can be an electro-optical and/or acousto-optical deflector and/or based on coherent beam combining.
  • the position offset device can receive the statistics clock signal and deflect the laser pulse accordingly.
  • an alternating voltage is used to generate an acoustic wave on a piezo crystal in an optically adjacent material, which periodically modulates the refractive index of the material.
  • the wave can propagate through the optical material, for example as a propagating wave or as a wave packet, or as a standing wave.
  • the periodic modulation of the refractive index creates a diffraction grating for an incident laser beam.
  • An incident laser beam is diffracted at the diffraction grating and thereby at least partially deflected at an angle to its original beam propagation direction.
  • the grating constant of the diffraction grating and thus the deflection angle depends, among other things, on the wavelength of the acoustic wave and therefore on the frequency of the applied alternating voltage.
  • Electro-optical deflectors are based on prisms made of electro-optical crystals. By applying a voltage, the refractive index of the electro-optical crystal is changed, so that the path of the laser beam through the prism changes.
  • the spatial statistical distribution with an electro-optical and/or acousto-optical deflector can be carried out with a clock speed of over 1 MHz. Accordingly, several million repositionings of the laser pulse can occur per second.
  • the electro-optical and/or acoustic deflectors can be used to reposition the laser pulses with individual pulse precision, so that each individual laser pulse is introduced at a different location in the material.
  • the position offset device can also be a wobble prism.
  • a wobble prism includes a prism that angularly deflects the laser beam.
  • a spatial deflection of the laser beam is achieved by mechanical deflection of the prism.
  • the wavelength of the laser pulses can be between 200nm and 3000nm. This makes it possible to adapt the process to many different materials and processing processes.
  • the repetition rate of the laser can be between 10kHz and 100MHz, in particular between 19kHz and 2MHz. The repetition rate determines the time interval at which at least two consecutive laser pulses are emitted.
  • the laser pulse can be composed of a large number of laser burst pulses, in particular composed of 2 to 100 laser burst pulses.
  • the laser burst pulses can be delivered with a particularly high frequency of over 1 GHz instead of a single laser pulse. In this case, instead of the single pulse deflection, the single laser burst pulse deflection occurs.
  • the fluence can be greater than 0.05J/cm A2 , in particular between 0.1J/cm A2 and 50J/cm A2 . This makes it possible to adapt the process to many different materials and processing processes.
  • the laser pulse duration can be between 10fs and 100ns, in particular between 100fs and 100ps.
  • the length of the laser pulses can be between 100ps and 100ns, in particular between 1 ns and 20ns, whereby the wavelength can be between 300nm and 550nm, in particular 355nm, whereby the repetition rate of the laser pulses can be between 10kHz and 100kHz, in particular between 10kHz and 50kHz, whereby the laser pulses can have an energy between 60pJ and 300pJ and 1 to 4 pulses can be emitted per spot.
  • the length of the laser pulses can be between 200fs and 1000fs, in particular between 300fs and 450fs, the wavelength can be between 900nm and 2300nm, in particular 1030nm, the repetition rate of the laser pulses can be between 10kHz and 400kHz, the laser pulses being in Laser bursts are emitted, each laser burst can contain between 2 and 4 laser pulses, the laser bursts can have an energy between 100pJ and 400pJ and the numerical aperture can be between 0.01 and 0.2, in particular 0.08.
  • the laser can in particular also comprise an unstable seed laser and an amplifier, the unstable seed laser containing the statistics generator and emitting laser pulses with a temporal statistical distribution, the amplifier amplifying the laser pulses of the seed laser.
  • the laser beam can also have a Gaussian beam shape or a non-diffractive beam shape.
  • Gaussian rays are understood to mean, in particular, rays whose intensity cross section corresponds to a Gaussian bell curve.
  • Non-diffracting rays and/or Bessel-like rays are understood to mean, in particular, rays in which a transverse intensity distribution is propagation-invariant.
  • a transverse intensity distribution along a longitudinal direction and/or propagation direction of the beams is essentially constant.
  • Non-diffractive laser beams therefore have the advantage that they can have an intensity distribution that is elongated in the direction of beam propagation and is significantly larger than the transverse dimensions of the intensity distribution.
  • material modifications that are elongated in the beam propagation direction can be produced, so that they can penetrate two sides of the workpiece particularly easily.
  • the laser beam can have a flattop beam shape and/or a supergaussian shape and/or a tophat beam shape.
  • Figure 1 shows a schematic structure of a device according to the status of
  • Figure 2A, B, C, D shows a further schematic structure of the device according to the invention
  • Figure 3 shows a further schematic structure of the device according to the invention.
  • Figure 4 shows a method according to the prior art
  • Figures 5A, B show a method according to the invention with spatial statistical distribution of the laser pulses;
  • Figures 6A, B show a method according to the invention with spatial and temporal statistics
  • Figure 7 shows a further method according to the invention with spatial and temporal statistical distribution of the laser pulses.
  • Figure 8 shows a further method according to the invention with spatial and temporal
  • the device has a system clock generator 1.
  • the system clock generator 1 preferably outputs signal pulses of a fixed frequency, the system clock signal.
  • the system clock generator 1 can be a pulse generator.
  • the system clock generator 1 is formed intrinsically in one of the other built-in device elements, as described further below.
  • the system clock generator 1 is set up to send the system clock signal to the statistics generator 2.
  • the statistics generator 2 receives the pulsed basic signal from the system clock generator 1 and can impose a statistical distribution on the pulses of the basic signal.
  • the statistics generator 2 can vary the intervals between the pulses of the system clock signal so that the signal pulses of the system clock signal have a statistical distribution.
  • the intervals between the pulses of the basic signal can be adjusted.
  • the statistical distribution can result from the time intervals between the adapted signal pulses and the unchanged pulses of the system clock signal.
  • These statistics clock signals can be received by the laser 3.
  • the laser 3 With each signal pulse that the laser 3 receives, the laser 3 can emit a laser pulse 300 which propagates along the laser beam 30 of the laser 3. This functionality is also called Pulse-On-Demand.
  • the laser pulse 30 can then be focused by processing optics 5 into a material 6 or onto the surface of a material 6. Accordingly, the laser pulses 300 are introduced with the statistical distribution of the statistics generator 2.
  • the laser pulse 300 can cause material processing in the material 6, so that processing of the material 6 takes place.
  • the feed device 4 can move the material 6 and the laser beam 30 relative to each other, so that the laser beam 30 is moved along the feed trajectory with a feed.
  • the feed device is designed as a scanner device with which the laser beam 30 is periodically moved over the material 6. If the laser pulses 300 with the statistical distribution are triggered during the feed and are introduced into the material 6, then the material modification is also present in the material 6 in a certain statistical distribution.
  • the statistical distribution of the laser pulses 300 is a temporal distribution, while the statistical distribution of the material modifications in the material 6 due to the simultaneous feed have a local statistical distribution.
  • a device according to the invention is shown in Figure 2A.
  • the pulse generation in the laser 3 is carried out analogously to FIG.
  • a position offset device 7 is arranged behind the laser 3 in the beam propagation direction.
  • the position offset device 7 can be, for example, an acousto-optical deflector.
  • the acousto-optical deflector 7 also receives the signal from the statistics generator 2 and can accordingly spatially deflect a laser pulse 300 triggered by the laser 3.
  • the temporal deviation of the signal pulse from the fundamental frequency can, for example, be translated into a spatial deflection.
  • the laser 3 can receive the statistics clock signal from the statistics generator 2 and impose a temporal variation on the laser pulses 300.
  • the feed device 4 can output the system clock signal and thus trigger a laser pulse 300, for example, after a certain distance has been covered.
  • the system clock signal can be influenced by the statistics generator 2, so that the position offset device 7 causes an additional spatial statistical distribution of the laser pulses 300.
  • the feed device 4 outputs the system clock signal and the system clock signal is influenced by the statistics generator 2.
  • the laser 3 can thus receive the statistical clock signal, with which, for example, a pulse triggering can be realized in accordance with the statistical distribution.
  • the position offset device 7 can cause a spatial statistical distribution of the laser pulses 300 through the received statistical signal.
  • the laser 3 it is also possible for the laser 3 to also receive the statistics clock signal and thereby impose an additional temporal statistical distribution.
  • the laser 3 comprises an unstable seed laser 34 and an amplifier 36. If the seed laser 34 receives a pulse of the basic signal of the system clock generator, the seed laser emits a laser pulse that is amplified by the amplifier. The temporal delivery of the laser pulse by the seed laser 34 is thereby inherently statistically distributed due to the instability.
  • Figure 4 shows a method according to the prior art.
  • Laser pulses are emitted at regular intervals and inserted into the material.
  • the laser pulses therefore only have one temporal frequency, namely the repetition frequency.
  • the material 6 can be moved uniformly relative to the laser beam 30 using a feed device.
  • the laser pulses 300 on the material 6 also have a uniform spacing, so that the laser pulses in the spatial frequency space only have one spatial frequency.
  • the laser 3 emits laser pulses 300 with a specific frequency, which correspond, for example, to the system clock of a system clock generator 1.
  • the triggered laser pulses fall on a position offset device 7 from which they are deflected.
  • the position offset device 7 can be controlled via the statistics generator 2, for example. Accordingly, the laser pulses 300 are deflected with the statistical distribution, for example deflected perpendicular to the feed direction. Due to the deflection of the laser pulses 300, the laser pulses are spatially statistically distributed around the feed trajectory.
  • FIG. 5B Such a method is shown in Figure 5B.
  • the laser beam 30 is periodically moved in a meandering manner over a material 6, while the laser pulses are deflected by the position offset device 7 perpendicular to the trajectory. Due to the even Pulse delivery, the laser pulses are present in a regular pattern in the y-direction, but have a spatial statistical distribution perpendicular to the meander structure.
  • the laser 3 can also emit laser pulses 300 with a temporal statistical distribution, for example by triggering a pulse-on-demand functionality of the laser 3 by the signal from the statistics generator 2. This is shown in Figure 6A.
  • the temporal statistical variation of the laser pulse output is noticeable at an existing feed rate in that the laser pulses 300 are also distributed along the feed direction, as shown in Figure 6B.
  • the laser pulses have a Gaussian distribution in both the x and y directions.
  • the laser pulses 300 are also offset from one another in the feed direction (at a constant feed speed).
  • the temporal statistical distribution and the spatial statistical distribution are different distributions, for example a triangular distribution and a uniform distribution.
  • the pulses of the system clock signal can be triggered at irregular intervals, for example because the feed device 4 only outputs such a system clock signal after a certain distance has been moved. In particular, at non-uniform speeds, such an irregular pulse emission can occur over time.
  • the statistics generator 2 receives the signal from the feed device 4, an additional temporal statistical distribution can be imposed so that the laser pulses are introduced into the material 6 at an irregular interval.

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • Lasers (AREA)
  • Laser Beam Processing (AREA)

Abstract

L'invention concerne un procédé et un dispositif de traitement d'un matériau au moyen d'impulsions laser d'un laser pulsé, les impulsions laser étant introduites dans le matériau afin de traiter le matériau, les impulsions laser (300) étant introduites dans le matériau (6) d'une manière distribuée spatialement et statistiquement autour d'une valeur cible spatiale, et la distribution statistique des impulsions laser pouvant être ajustée et adaptée en fonction du débit d'alimentation actuel.
PCT/EP2023/073377 2022-09-09 2023-08-25 Dispositif et procédé de traitement d'un matériau au moyen d'impulsions laser qui sont introduites statistiquement et spatialement autour d'une valeur cible spatiale WO2024052137A1 (fr)

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DE102022122964.5A DE102022122964A1 (de) 2022-09-09 2022-09-09 Vorrichtung und Verfahren zum Bearbeiten eines Materials
DE102022122964.5 2022-09-09

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US20140217058A1 (en) * 2011-09-23 2014-08-07 Boegli-Gravures S.A. Method and device for producing a structured surface on a steel embossing roller
US20180207748A1 (en) 2017-01-23 2018-07-26 Lumentum Operations Llc Machining processes using a random trigger feature for an ultrashort pulse laser
DE102017006358A1 (de) 2017-07-06 2019-01-10 Forschungszentrum Jülich GmbH Verfahren zur Strukturierung einer Substratoberfläche
EP3613228A1 (fr) 2017-04-17 2020-02-26 Qomplx, Inc. Système de commutation basé sur la réglementation pour routage de message électronique
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US20140217058A1 (en) * 2011-09-23 2014-08-07 Boegli-Gravures S.A. Method and device for producing a structured surface on a steel embossing roller
US20200399175A1 (en) * 2016-03-29 2020-12-24 Corning Incorporated Glass articles comprising light extraction features and methods for making the same
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EP3613228A1 (fr) 2017-04-17 2020-02-26 Qomplx, Inc. Système de commutation basé sur la réglementation pour routage de message électronique
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